1. Field of the Invention
The present invention relates to an image processing apparatus for concentration modulating input image data.
2. Related Background Art
Hitherto, an apparatus which can execute a process (hereinafter, referred to as a texture process) for concentration modulating image data by using arbitrary pattern data has been limited to a relatively large scale computer. The texture process will now be briefly described. For instance, the texture process denotes that an input image as shown in FIG. 7A is concentration modulated by using pattern data as shown in FIG. 7B, so that an output image as shown in FIG. 7C is obtained. Assuming that the texture pattern of FIG. 7B is a pattern of a cloth design, for example, the cloth pattern can be synthesized to the area in the L-shaped character of FIG. 7A.
In an image processing apparatus for outputting an image from an image input in a real-time manner, the apparatus which can execute such a texture process does not exist.
On the other hand, hitherto, in the case of executing the texture process on a plurality of areas, the process must be sequentially executed for every area, which is troublesome. Therefore, in the case of synthesizing the same texture pattern with each of a plurality of areas, it takes time in proportion to the number of areas.
In addition, in the case of executing the texture process on a non-rectangular area instead of a rectangular area, a mask must be produced to designate such an area, which is very complicated.
Further, in the case of variably magnifying a texture pattern and executing concentration modulation thereof with the input image data, after the variably magnifying process is executed on the texture pattern every process, the texture process must be performed, which is troublesome.
On the other hand, for instance, an apparatus of a construction shown in FIG. 1 is considered as a method of realizing the texture process executed on an input image in a real-time manner. That is, according to this method, a pattern image for the texture process is read and in advance, and when an original image which is to be subjected to the texture process is read, the stored pattern image is read out and calculated by an image modulator and the concentration is modulated.
However, in such an apparatus, since there is a limitation in the capacity of a memory unit to store the pattern image for the texture process, if the pattern image to be processed is smaller than the original image data to be processed, the pattern image must be repetitively used.
In the case of repetitively using the pattern image as mentioned above, no problem occurs for an image such that the patterns are relatively continuous at the right/left and upper/lower joint surfaces of the pattern image. However, in many cases, since the patterns at the joint surfaces are discontinuous, there is a drawback that the image after completion of the texture process suddenly changes at the joint surfaces of the pattern and an unnatural line of the concentration difference appears in the image. For instance, FIG. 16A shows a finite size pattern. FIG. 16B shows concentration difference lines which are generated when the texture process of the repetitive pattern was executed to an area larger than the size of the finite size pattern of FIG. 16A.
Such a drawback inevitably occurs in the image process for concentration modulating an image in accordance with a certain pattern.